The invention relates to an apparatus for returning the cooling lubricant adhering to the swarf during the machining of metals in a machine tool, which lubricant becomes detached during the discharge of the swarf on an endless rotating steel hinge belt, in which case the hinge belt is guided in a full box frame constructed as a swarf conveyor, which consists of a straight flat box part and of a box-like ascending part and whereof the straight flat box part in accordance with its feed length can be pushed below the machine bed of the machine tool so that falling swarf immediately arrives on the hinge belt and the cooling lubricant runs down or trickles into the full box frame through the hinges or through additional holes in the hinge belt.
Systems of this type for separating swarf and coolant are known as swarf conveyors (Mayfran prospectus of swarf conveyors of the co-applicant) and are used widely in practical operation. A typical form of swarf conveyor consists of a straight flat box part with an adjoining ascending part, which is likewise constructed as a box frame. The length of the straight flat box part, which is known as the feed length, thus depends on whether one or more machine tools are to be served by the swarf conveyor. The endless hinge belt revolves in the full box frame. For operation, the swarf conveyor with the flat box section is set up below the machine run of a machine tool and the ascending part projects upwards beside the machine, where sufficient space is available, since below the machine bed itself, the available vertical space amounts to only approximately 40 cm, which is then almost completely filled by the flat box of the swarf conveyor. The quantity of swarf produced is continuously discharged and at the end of the ascending part drops from the hinge belt into a swarf container provided below the ascending part. During the conveying time, the cooling lubricant trickles or drips through the hinge belt and collects in the full box frame. From here the cooling lubricant is returned to the machine tool by means of pumps.
Since in most cases, the separate and external settingup of a filter unit anywhere close to the machine tool, to which the cooling lubricant from the swarf conveyor must firstly be pumped, proves unsuitable for reasons of space, hitherto it was tolerated that the cooling lubricant collected and re-supplied to the consumer, which still contains very fine swarf due to its previous use, has an unfavourable effect on the workpiece as regards the surface quality and on the tool as regards the reduction of its service life. Added to this is the fact that the life expectancy of the cooling lubricant is reduced by increasing contamination.